Interatrial Septal Mass Secondary to Rosai-Dorfman Disease

Varying degrees of atrioventricular block can be associated with old age or a manifestation of an ischemic, metabolic, or infective pathology. In patients with no clear explanation, it is important to investigate secondary causes. Our case describes the first case of an adult with Rosai-Dorfman histiocytosis presenting with complete heart block. (Level of Difficulty: Advanced.)


HISTORY OF PRESENTATION
A 54-year-old, African woman presented with a 2month history of chest tightness with associated shortness of breath and dizziness. An electrocardiogram was conducted that showed third-degree heart block, prompting further investigation ( Figure 1).

MEDICAL HISTORY
She had a background of Rosai-Dorfman disease (RDD) with bony involvement, type 2 diabetes mellitus, and first-degree atrioventricular (AV) block. Her only medication history was metformin 500 mg twice a day. Previously, she had a histiocytic lesion in the right hip that resulted in a fragility fracture requiring a right total hip replacement. Furthermore, there was a lesion in the left hip that was being monitored and a lesion in the left sacrum that required radiotherapy.

DIFFERENTIAL DIAGNOSIS
Differential diagnosis included all causes of pathologic blockade of AV conduction, including infective, metabolic, pharmacologic, and structural disturbances.

INVESTIGATIONS
Initial blood results demonstrated a normal blood count, electrolytes, and thyroid function, and chest x-ray appeared normal with no signs of infection. Due to a high index of suspicion for structural cardiac disease, it was decided to carry out cardiac magnetic resonance imaging (MRI) in the first instance.

LEARNING OBJECTIVES
To describe the presentation of a rare hematologic disorder presenting with an IAS mass.
To demonstrate the utility of multimodality imaging for identifying the etiology of an intracardiac mass.
Cardiac MRI was performed using a 1.5-T Siemens Aera scanner; steady-state free precession cine imaging, T1-weighted imaging pre-and post-gadolinium-based contrast, T2weighted imaging, pre-contrast T1 and T2 mapping, and early-and late-gadolinium enhancement images were acquired.

MANAGEMENT
Given the location of the IAS mass, it was agreed that resection would not be feasible due to its association with surrounding structures including mitral apparatus, interventricular septum, and coronary sinus.
Medical management of the RDD was discussed but, because the progression of the disease was uncertain, it was agreed that on balance the patient should be offered a dual-chamber pacemaker. Ten months later she presented with clinical heart failure and significantly impaired left ventricular systolic function most likely as a result of pacing-induced cardiomyopathy. She underwent an attempted upgrade to biventricular pacing, however, we were unable to successfully cannulate the coronary sinus and she was implanted with a left bundle area pacing lead for resynchronization.

DISCUSSION
RDD is an uncommon histiocytic disorder, which classically presents with massive bilateral painless cervical lymphadenopathy associated with weight loss, fevers, and night sweats. 1 Most seen in African patients with a male predominance, the disease can be split into either sporadic or familial and cutaneous RDD. 1 Extranodal disease has been reported in >40% of patients with common sites being the skin, nasal Given the scarcity of reported cardiac involvement of RDD, the optimal approach to management remains unclear. The most recent consensus of management (2018) suggests that the disease progression is often unpredictable, and that extranodal involvement is often associated with a poor prognosis. 6 In our case, the presence of first-degree heart block 2 years before any cardiac imaging suggests there had been intracardiac involvement of Rosai-Dorfman that was not rapidly expanding. This was in the context of no systemic treatment for the disease because the previously discovered bony lesion was managed with localized radiotherapy. This may give some indication of the natural progression of the disease, but further studies are required before this can be confirmed.

FOLLOW-UP
After implantation of the permanent pacemaker, pacing parameters remained stable, however, she developed clinical heart failure with new depression of left ventricular systolic function hence the decision for upgrade to resynchronization. Our patient was offered systemic steroid treatment as an attempt to limit the growth of the interatrial mass, but this was declined due to the side effect profile of systemic glucocorticoids. As such, the patient will remain under follow-up and is planned for interval imaging to assess the progression of the mass.

CONCLUSIONS
Understanding the pathophysiology remains a key component to managing patients with complete heart block and this is highlighted in the current European Society of Cardiology 2021 pacing guidelines. 7 This case demonstrates the value of multimodality cardiac imaging in a young patient with RDD to allow for identification of cardiac involvement. Management of masses should be agreed using input from multiple specialists given the lack of data to guide treatment.

FUNDING SUPPORT AND AUTHOR DISCLOSURES
The authors have reported that they have no relationships relevant to the contents of this paper to disclose. ADDRESS FOR CORRESPONDENCE: Dr Abdul Hadi Butt, 9 The Close, Dartford, DA2 7ES, United Kingdom. E-mail: abdul.butt@gstt.nhs.uk.